DOCSLIB.ORG

Chapter 21. Regulation of Calcium and Magnesium

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chapter 21. Regulation of Calcium and Magnesium SECTION 111 Mineral Homeostasis (Section Editor: Ego Seeman) 21. Regulation of Calcium and Magnesium .......................................................................................... 104 Murray J. Favus and David Goltznian 22. Fetal Calcium Metabolism ......................... 108 Christopher S. Kovacs 23. Fibroblast Growth Factor-23 112 24. Gonadal Steroids . .................................................................................................................... 117 Kutrien Venken, Steven Boonen, Roger Bouillon, rind Dirk Vander~schueren 25. Parathyroid Hormone ........................................................................................................................................................................ 123 Robert A. Nissenson and Harald Jiippner 26. Parathyroid Hormone-Related Protein .......................................................................................................................................... 127 John J. Wysolmerski 27. Ca*+-SensingReceptor ...................................................................................................................................................................... 134 Edward M. Brown 28. Vitamin D: Production, Metabolism, Mechanism of Action, and Clinical Requirements .................................................... 141 Daniel Bikle, John Adam, and Sylvia Christakos 0 2008 American Society for Bone and Mineral Research 103 Chapter 21. Regulation of Calcium and Magnesium Murray J. Favusl and David Goltzman’ ‘Department of Medicine, University of Chicugo, Chicugo, Illinois; ”Center for Advanced Bone and Periodontul Research, McCill University, Montreul, Quebec, Chnrirlu CALCIUM hancing it. Consequently major shifts in serum protein or pH requires direct measurement of the ionized Ca level to deter- Distribution mine the physiologic serum calcium level. Total Body Distribution. In adults, the body contains -1000 g of Ca, of which 99% is located in the mineral phase of bone as Mineral Homeostasis the hydroxyapatite crystal [Ca,,,(PO,),(OH),]. The crystal The ECF concentration of calcium is tightly maintained plays a key role in the mechanical weight-bearing properties of within a rather narrow range because of the importance of the bone and serves as a ready source of Ca to support a number Ca ion to numerous cellular functions including cell division, of Ca-dependent biological systems and to maintain blood ion- cell adhesion and plasma membrane integrity, protein secre- ized Ca within the normal range. The remaining 1% of total tion. muscle contraction, neuronal excitability, glycogen me- body Ca is located in the blood, extracellular fluid, and soft tabolism, and coagulation. tissues. In serum, total Ca is lo-’ M and is the most frequent The skeleton, the gut, and the kidney each plays a major role measurement of serum Ca levels. Of the total Ca, the ionized in assuring Ca homeostasis. Overall, in a typical individual, if fraction (50%) is the biologically functional portion of total Ca 1000 mg of Ca is ingested in the diet per day, -200 mg will be and can be measured clinically; 40% of the total is bound to absorbed. Approximately 10 g of Ca will be filtered daily albumin in a pH-dependent manner; and the remaining 10% through the kidney, and most will be reabsorbed, with -200 mg exists as a complex of either citrate or PO, ions. being excreted in the urine. The normal 24-h excretion of Ca Cell Levels. Cytosol Ca is -10-‘ M, which creates a 1000-fold may, however, vary between 100 and 300 mg/d (2.5-7.5 mmol/ gradient across the plasma membrane (extracellular fluid d). The skeleton, a storage site of -1 kg of Ca, is the major Ca [ECF] Ca is lo-’ M) that favors Ca entry into the cell. There reservoir in the body. Ordinarily, as a result of normal bone is also an electrical charge across the plasma membrane of -50 turnover, -500 mg of Ca is released from bone per day, and the mV with the cell interior negative. Thus, the chemical and equivalent amount is accreted per day (Fig. 1). electrical gradients across the plasma membrane favor Ca en- Tight regulation of the ECF calcium concentration is main- try, which the cell must defend against to preserve cell viability. tained through the action of Ca-sensitive cells that modulate Ca-induced cell death is largely prevented by several mecha- the production of These hormones act on spe- nisms including extrusion of Ca from the cell by ATP- cific cells in bone, gut, and kidney, which can respond by al- dependent energy driven Ca pumps and Ca channels; Na-Ca tering fluxes of Ca to maintain ECF Ca. Thus, a reduction in exchangers; and binding of intracellular Ca by proteins located ECF Ca stimulates release of PTH from the parathyroid glands in the cytosol, endoplasmic reticulum (ER), and mitochondria. in the neck. This hormone can act to enhance bone resorption Ca binding to ER and mitochondria1 sites buffer intracellular and liberate both Ca and phosphate from the skeleton. FTH Ca and can be mobilized to maintain cytosol Ca levels and to can also enhance Ca reabsorption in the kidney while at the create pulsatile peaks of Ca to mediate membrane receptor same time inhibit phosphate reabsorption producing phospha- signaling that regulate a variety of biological systems. turia. Hypocalcemia and PTH itself can both stimulate the conversion of the inert metabolite of vitamin D, 25- Blood Levels. Ca in the blood is normally transported partly hydroxyvitamin D, [25(OH)D,] to the active moiety 1,25- bound to plasma proteins (-45%), notably albumin, partly dihydroxyvitamin D, [1,25(OH),D,],‘”’ which in turn will en- bound to small anions such as phosphate and citrate (-10Y0), hance intestinal Ca absorption, and to a lesser extent, renal and partly in the free or ionized state (-45%).“’ Although only phosphate reabsorption. The net effect of the mobilization of the ionized Ca is available to move into cells and activate Ca from bone, the increased absorption of Ca from the gut, cellular processes, most clinical laboratories report total serum and the increased reabsorption of filtered Ca along the neph- Ca concentrations. Concentrations of total Ca in normal serum ron is to restore the ECF Ca to normal and to inhibit further generally range between 8.5 and 10.5 mg/dl (2.12-2.62 mM), production of PTH and 1,25(OH),D,. The opposite sequence and levels above this are considered to be hypercalcemic. The of events [i.e., diminished PTH and 1,25(OH),D, secretion], normal range of ionized Ca is 4.65-5.25 mgidl (1.16-1.31 mM). along with Stimulation of renal Ca sensing receptor (CaSR), When protein concentrations, and especially albumin concen- occurs when the ECF Ca is raised above the normal range. The trations, fluctuate, total Ca levels may vary, whereas the ion- effect of suppressing the release of PTH and 1,25(OH),D, and ized Ca may remain relatively stable. Dehydration or hemo- stimulating CaSR diminishes skeletal Ca release, decreases in- concentration during venipuncture may elevate serum albumin testinal Ca absorption and renal Ca reabsorption, and restores and falsely elevate total serum Ca. Such elevations in total Ca, the elevated ECF Ca to normal. when albumin levels are increased, can be “corrected” by sub- tracting 0.8 mg/dl from the total Ca for every 1.0 gidl by which PTH and 1,25(OH),D, Actions on Target Tissues the serum albumin concentration is >4 g/dl. Conversely, when Intestinal Ca Transport. Net intestinal Ca absorption can be albumin levels are low, total Ca can be corrected by adding 0.8 determined by the external balance technique in which a diet mg/dl for every 1.0 g/dl by which the albumin is <4 g/dl. Even of known composition with a known amount of Ca is ingested, in the presence of a normal serum albumin, changes in blood and urine Ca excretion and fecal Ca loss are measured. Nega- pH can alter the equilibrium constant of the albumin-Ca2’ tive absorption occurs when net absorption declines to -200 complex, with acidosis reducing the binding and alkalosis en- mg Ca/d (5.0 mmol). The portion of dietary Ca absorbed varies with age and amount of Ca ingested and may vary from 20% The authors state that they have no conflicts of interest to 60%. Rates of net Ca absorption are high in growing chil- 104 0 2008 American Society for Bone and Mineral Research REGUL.ATIONOF CALCIUM AND MAGNESIUM/ 105 FIG. 1. Calcium balance. On average, in a typical adult, -1 g of elemental calcium (Ca+') is ingested per day. Of this, -200 mg/d will be absorbed and 800 mgid excreted. Approximately 1 kg of Ca is stored in bone and -SO0 mgid is released by resorption or deposited during bone formation. Of the 10 g of Ca filtered through the kidney per day, only -200 mg or less ap- pears in the urine, the remainder being reabsorbed. dren; during grow spurts in adolescence; and during pregnancy Renal Ca Handling. The kidney plays a central role in ensur- and lactation. The efficiency of Ca absorption increases during ing Ca balance, and PTH has a major role in fine-tuning this prolonged dietary Ca restriction to absorb the greatest portion renal function("'-l2) by stimulating both renal Ca reabsorption of that ingested. Net absorption declines with age in men and (proximal tubule) and excretion (distal nephron). Multiple in- women, and so increased Ca intake is required to compensate fluences of Ca handling are listed in Table 2. Descriptions of for the lower absorption rate. Fecal Ca losses vary between 100 the molecular actions of PTH on the kidney are found else- and 200 mg/d (2.5-5.0 mmol). Fecal Ca is composed of unab- where in the Primer. PTH has little effect on modulating Ca sorbed dietary Ca and Ca contained in intestinal, pancreatic, fluxes in the proximal tubule where 65% of the filtered Ca is and biliary secretions. Secreted Ca is not regulated by hor- reabsorbed, coupled to the bulk transport of solutes such as mones or serum Ca. sodium and water.'") In this nephron region, PTH can also Because of the large surface area of the duodenum and stimulate the 25(OH)D,-la hydroxylase la(OH)ase], leading jejunum, 90% of absorbed Ca occurs in these regions.
Load more

Recommended publications
  • Effect-Of-Various-Calcium-Salts.Pdf
    Journal of Trace Elements in Medicine and Biology 49 (2018) 8–12 Contents lists available at ScienceDirect Journal of Trace Elements in Medicine and Biology journal homepage: www.elsevier.com/locate/jtemb Effect of various calcium salts on non-heme iron bioavailability in fasted women of childbearing age T Valeria Candiaa, Israel Ríos-Castilloa,b, Frank Carrera-Gilc, Berta Vizcarraa, Manuel Olivaresa, ⁎ Sotiris Chaniotakisd, Fernando Pizarroa, a Laboratory of Micronutrients, Institute of Nutrition and Food Technologies, University of Chile, Santiago, Chile b Food and Agriculture Organization of the United Nations, Sub Regional Office for Mesoamerica. Panama City, Panama c Nutrition and Dietetic Department, Fundación Valle del Lili Academic Hospital, Cali, Colombia d Department of Graduate Medical Sciences, Boston University School of Medicine, Boston, United States ARTICLE INFO ABSTRACT Keywords: Introduction: Micronutrient deficiencies are one of the most important public health issues worldwide and iron Iron bioavailability (Fe) deficiency anemia is the most prevalent micronutrient deficiency. Iron deficiency often coexists with cal- Iron absorption cium deficiency and iron and calcium supplementation often overlap. This has led to investigations into the Iron interaction between these two minerals, and whether calcium may inhibit iron absorption in the gut. Calcium Objective: To determine the effect of various calcium salts on non-heme iron bioavailability in fasted women of Women childbearing age. Methods: A randomized and single blinded trial was conducted on 27 women of childbearing age (35–45 years old) divided into 2 groups (n1 = 13 and n2 = 14, respectively). On four different days, after an overnight fast, 55 59 they received 5 mg of Fe as FeSO4 (labeled with Fe or Fe) with 800 mg of elemental calcium in the form of either calcium chloride, calcium gluconate, calcium citrate, calcium carbonate, calcium lactate, calcium sulfate or calcium phosphate.
    [Show full text]
  • Copper, Magnesium, Zinc and Calcium Status in Osteopenic and Osteoporotic Post-Menopausal Women
    02-Mahdaviroshan_- 25/05/15 15:48 Pagina 18 Mini-review Copper, magnesium, zinc and calcium status in osteopenic and osteoporotic post-menopausal women Marjan Mahdavi-Roshan 1 seems to be due to an imbalance between bone resorption and Mehrangiz Ebrahimi 2 bone formation at older ages (1-3), and is widely recognized as Aliasgar Ebrahimi 3 a major public health problem, especially for women (4). Osteopenia, defined as a bone mineral density that is lower than normal but not low enough to be classified as osteo - 1 Department of Community Medicine, School of Medicine, porosis, generally increases in severity with age and is most Guilan University of Medical Science, Rasht, Iran prevalent in women who are postmenopausal. Osteopenia is 2 Faculty of Health and Nutrition Sciences, Tabriz University often called ‘pre-osteoporosis’ as it sometimes leads to os - of Medical Sciences, Tabriz, Iran teoporosis (5). The etiology of osteoporosis and osteopenia 3 Department of Rheumatology, School of Medicine, Tabriz, is multi-factorial. Many factors – genetic differences, en - University of Medical Sciences, Tabriz, Iran docrine factors and lifestyle behaviour, such as physical ac - tivity and diet, especially mineral deficiency due to reduced dietary intake and reduced absorption of these nutrients – are thought to play important role in osteopenia or osteo - Address for correspondence: porosis and its prevention (5, 6). Marjan Mahdavi-Roshan Minerals such as magnesium, zinc, copper and calcium are Department of Community Medicine all essential for health. They help promote strong bones and School of Medicine, Guilan University of Medical Science are involved in the interaction of more than 300 enzyme re - Rasht, Iran actions.
    [Show full text]
  • Reviews on the Mineral Provision in Ruminants (VIII): IRON METABOLISM and REQUIREMENTS in RUMINANTS
    Reviews on the mineral provision in ruminants (VIII): IRON METABOLISM AND REQUIREMENTS IN RUMINANTS A.M. van den Top CVB Documentation report nr. 40 November 2005 Centraal Veevoederbureau Centraal Veevoederbureau 2005 All rights are explicitly reserved. No part of this publication may be reproduced, distributed and/or published by any means (including but not limited to printing, photocopying, microfilming, scanning, electronic copying or distribution) in whatever manner, without the prior written consent of the Centraal Veevoederbureau. Although this publication has been compiled with great care, the Centraal Veevoederbureau cannot be held liable in any way for the consequences of any use of the information contained in this publication. Reviews on the mineral provision in ruminants (VIII): IRON METABOLISM AND REQUIREMENTS IN RUMINANTS A.M. van den Top Adviesbureau VOER-RAAD Groenekan, The Netherlands CVB Documentation report nr. 40 November 2005 Centraal Veevoederbureau Postbus 2176 8203 AD Lelystad Telefoon 0320 – 29 32 11 Telefax 0320 – 29 35 38 E-mail [email protected] Internet www.cvb.pdv.nl PREFACE In the Netherlands the ´Handleiding Mineralenonderzoek bij rundvee in de praktijk´1 is a well- known publication that has been used already for decades as a guide to trace and treat mineral disorders in cattle. The fifth edition of this guidebook was published in 1996. The content of this publication was largely identical to that of the fourth edition (1990). Therefore the (independent) committee that is responsible for the contents of the guidebook (the ‘Commissie Onderzoek Minerale Voeding’2, COMV) decided in 2000 that a thorough revision was desired. The committee was of the opinion that, if possible, the available scientific literature should be summarized and evaluated once again.
    [Show full text]
  • 47 Amphibian Calcium Metabolism
    J. exp. Biol. 184, 47–61 (1993) 47 Printed in Great Britain © The Company of Biologists Limited 1993 AMPHIBIAN CALCIUM METABOLISM DANIEL F. STIFFLER Biological Sciences Department, California State Polytechnic University, Pomona, CA 91768, USA Summary Calcium is present in amphibian blood at a concentration similar to that in other vertebrates, about 1–2mmol l21. The fraction of free calcium in amphibians is lower than that in other tetrapod vertebrates because about 50% of the plasma Ca2+ is bound to plasma proteins and perhaps other molecules. Plasma [Ca2+] varies seasonally, increasing in spring and summer and decreasing in winter. Changes in plasma [Ca2+] also occur during larval development, as the concentration of this ion increases in larval forms as they approach metamorphosis. Calcium is exchanged at a variety of sites in animals. There is evidence for Ca2+ uptake across the skin and gills of larval anurans. It is also transported into the blood from the small intestine (especially the duodenum) and reabsorbed in renal tubules from the glomerular filtrate. The possibility of Ca2+ absorption from urine stored in the urinary bladder has not been confirmed, however. Calcium is stored in bone and in specialized endolymphatic sacs. This Ca2+ can be mobilized when the need arises. There are a number of endocrine and other humoral factors that appear to be involved in amphibian calcium metabolism. These include parathyroid hormone, calcitonin, vitamin D and prolactin. Introduction The study of amphibian calcium metabolism has lagged behind the study of other major ions such as Na+, K+ and Cl2 for several reasons. The interest created in Na+, K+ and Cl2 by the early work of Krogh (1937) and Ussing (1949) stimulated a large number of workers to study the transport of these ions in frog skin.
    [Show full text]
  • Effects of Copper on Calcium Metabolism and Detoxification Mechanisms in Freshwater Bivalve Species of Anodonta
    University of Bayreuth, Germany Chair of Environmental Chemistry and Ecotoxicology & University of Lorraine, France Laboratory of Interactions Ecotoxicology Biodiversity Ecosystems Thesis submitted in fulfillment of the degree of Doctor in Sciences Discipline: Ecotoxicology Effects of copper on calcium metabolism and detoxification mechanisms in freshwater bivalve species of Anodonta Olivier SANTINI 13 June 2012 Supervisors: Professor Hartmut FRANK Professor Paule VASSEUR University of Bayreuth, Germany Chair of Environmental Chemistry and Ecotoxicology & University of Lorraine, France Laboratory of Interactions Ecotoxicology Biodiversity Ecosystems Thesis submitted in fulfillment of the degree of Doctor in Sciences Discipline: Ecotoxicology Effects of copper on calcium metabolism and detoxification mechanisms in freshwater bivalve species of Anodonta Olivier SANTINI 13 June 2012 Supervisors: Professor Hartmut FRANK Professor Paule VASSEUR Jury of thesis: Lecturer-HDR Carole COSSU-LEGUILLE, University of Lorraine, France Professor Konrad DETTNER, University of Bayreuth, Germany, reviewer Professor Hartmut FRANK, University of Bayreuth, Germany, reviewer Professor Britta PLANER-FRIEDRICH, University of Bayreuth, Germany, chairman Professor Jouni TASKINEN University of Jyväskylä, Finland, reviewer Professor Paule VASSEUR University of Lorraine, France, reviewer This doctoral thesis was prepared at the Departement of Environmental Chemistry and Ecotoxicology in the University of Bayreuth supervised by Prof. Dr. Hartmut Frank, and in the Laboratory Interactions Ecotoxicology Biodiversity Ecosystems in the University of Lorraine supervised by Prof. Dr. Paule Vasseur, from 01/10/2006 until 13/06/2012. This is a full reprint of the dissertation submitted to attain the academic degree of the Doctor of Natural Sciences (Dr. rer. nat.) and approved by the Faculty of Biology, Chemistry and Geosciences of the University of Bayreuth.
    [Show full text]
  • Association of Vitamin D and FGF23 with Serum
    Saki et al. BMC Nephrology (2020) 21:482 https://doi.org/10.1186/s12882-020-02101-3 RESEARCH ARTICLE Open Access Association of vitamin D and FGF23 with serum ferritin in hypoparathyroid thalassemia: a case control study Forough Saki, Azita Salehifar, Seyed Reza Kassaee and Gholamhossein Ranjbar Omrani* Abstract Background: FGF23 controls serum l,25(OH)2D3 levels and phosphate homeostasis. This study evaluates the effects of ferritin on intact PTH, FGF23, and l,25(OH)2D3 in patients with major thalassemia. It also evaluates FGF23 changes in patients with hypoparathyroidism to clarify the interaction between FGF23 and PTH in the absence of proper PTH functioning in human. Methods: In this case-control study, 25 major-beta thalassemia patients with hypoparathyroidism were age- and gender-matched with major-beta thalassemia patients having normal parathyroid function. Biochemical studies assessed the serum calcium, albumin, phosphorus, alkaline phosphatase, PTH, FGF23, 25(OH) D, 1,25(OH)2D3, ferritin, and the fractional excretion of phosphorous. Results: FGF23 was higher in the patients with hypoparathyroidism than the controls (P = 0.002). The fractional excretion of phosphorous was lower in patients with hypoparathyroidism, despite the high level of FGF23 (P = 0.001). There was a correlation between serum 1,25(OH)2D3 and FGF23 with ferritin in the controls (P = < 0.001and P = < 0.001, respectively). Conclusions: The present study showed a strong positive correlation between serum ferritin and levels of FGF23 and 1,25(OH)2D3. We hypothesized that ferritin could have a stimulatory effect on the production of 1,25(OH)2D3. Moreover, a rise in FGF23 in patients with thalassemia, might be either associated with the stimulating effect of PTH and 1,25(OH)2D3, or directly related to the stimulating effect of ferritin.
    [Show full text]
  • Tissue Mineral Levels in Victims of Sudden Infant Death Syndrome 11
    784 ERICKSON ET AL. 27. Underwood, E. J.: Trace elements in human and animal nutrition. 4th ed. p. 410. 30. Requests for reprints should be addressed to: Dr. Marilyn M. Erickson, Depart- (Academic Press, New York, 1977). ment of Pediatrics, St. Louis Children's Hospital, P.O. Box 14871, St. Louis, 28. Ziegler, E. E., Edwards, B. B., Jensen, R. L., Mahaffey, K. R., and Foman, S. J.: MO 63178 Absorption and retention of lead by infants. Pediatr. Res., 12: 29 (1978). 31. This research was supported in part by NIH grant No. 5T32 AM07033. 29. This work is taken in part from a dissertation submitted to the Graduate School, 32. This research was supported in part by NIH grant No. HD-09998-04. St. Louis University by M. M. Erickson in partial fulfillment ofthe requirement 33. Received for publication June 22, 1982. for the Ph.D. degree in Pathology. 34. Accepted for publication March 15, 1983. 003 I-3998/83/ 17 10-0784$02.00/0 PEDIATRIC RESEARCH Vol. 17, No. 10, 1983 Copyright O 1983 International Pediatric Research Foundation, Inc. Printed in (I.S.A. Tissue Mineral Levels in Victims of Sudden Infant Death Syndrome 11. Essential Minerals: Copper, Zinc, Calcium, and Magnesium(45) MARILYN M. ERICKSON,'~~~~~)ALPHONSE POKLIS, GEORGE E. GANTNER, ALLAN W. DICKINSON, AND LAURA S. HILL MAN'^" The Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine; the Division of Neonatology; St. Louis Children's Hospital; the Division of Bone and Mineral Metabolism, the Jewish Hospital of St. Louis; the Management Information and Systems Department, Monsanto Company; the Department of Pathology, St.
    [Show full text]
  • The Multiple Facets of Iron Recycling
    G C A T T A C G G C A T genes Review The Multiple Facets of Iron Recycling Patryk Slusarczyk and Katarzyna Mleczko-Sanecka * Laboratory of Iron Homeostasis, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-22-597-07-76 Abstract: The production of around 2.5 million red blood cells (RBCs) per second in erythropoiesis is one of the most intense activities in the body. It continuously consumes large amounts of iron, approximately 80% of which is recycled from aged erythrocytes. Therefore, similar to the “making”, the “breaking” of red blood cells is also very rapid and represents one of the key processes in mammalian physiology. Under steady-state conditions, this important task is accomplished by specialized macrophages, mostly liver Kupffer cells (KCs) and splenic red pulp macrophages (RPMs). It relies to a large extent on the engulfment of red blood cells via so-called erythrophagocytosis. Surprisingly, we still understand little about the mechanistic details of the removal and processing of red blood cells by these specialized macrophages. We have only started to uncover the signaling pathways that imprint their identity, control their functions and enable their plasticity. Recent findings also identify other myeloid cell types capable of red blood cell removal and establish reciprocal cross-talk between the intensity of erythrophagocytosis and other cellular activities. Here, we aimed to review the multiple and emerging facets of iron recycling to illustrate how this exciting field of study is currently expanding. Keywords: iron homeostasis; hemolysis; heme; hemoglobin; ferroportin; hepcidin Citation: Slusarczyk, P.; Mleczko-Sanecka, K.
    [Show full text]
  • 2 Overview of Calcium
    Dietary Reference Intakes for Calcium and Vitamin D 2 Overview of Calcium INTRODUCTION Calcium as a nutrient is most commonly associated with the formation and metabolism of bone. Over 99 percent of total body calcium is found as calcium hydroxyapatite (Ca10[PO4]6[OH]2) in bones and teeth, where it provides hard tissue with its strength. Calcium in the circulatory system, extracellular fluid, muscle, and other tissues is critical for mediating vas- cular contraction and vasodilatation, muscle function, nerve transmission, intracellular signaling, and hormonal secretion. Bone tissue serves as a res- ervoir for and source of calcium for these critical metabolic needs through the process of bone remodeling. Calcium metabolism is regulated in large part by the parathyroid hor- mone (PTH)–vitamin D endocrine system, which is characterized by a series of homeostatic feedback loops. The rapid release of mineral from the bone is essential to maintain adequate levels of ionized calcium in se- rum. During vitamin D deficiency states, bone metabolism is significantly affected as a result of reduced active calcium absorption. This leads to in- creased PTH secretion as the calcium sensing receptor in the parathyroid gland senses changes in circulating ionic calcium. Increased PTH levels induce enzyme activity (1α-hydroxylase) in the kidney, which converts vi- tamin D to its active hormonal form, calcitriol. In turn, calcitriol stimulates enhanced calcium absorption from the gut. Not surprisingly, the interplay between the dynamics of calcium and vitamin D often complicates the interpretation of data relative to calcium requirements, deficiency states, and excess intake. 35 Copyright © National Academy of Sciences.
    [Show full text]
  • Models to Assess Food Iron Bioavailability Seth Mensah Armah Iowa State University
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2014 Models to assess food iron bioavailability Seth Mensah Armah Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Human and Clinical Nutrition Commons Recommended Citation Armah, Seth Mensah, "Models to assess food iron bioavailability" (2014). Graduate Theses and Dissertations. 14085. https://lib.dr.iastate.edu/etd/14085 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Models to assess food iron bioavailability by Seth Mensah Armah A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Nutritional Sciences (Human Nutrition) Program of Study Committee: Manju Reddy, Co-Major Professor Alicia Carriquiry, Co-Major Professor James Hollis Wendy White Sarah Francis Iowa State University Ames, Iowa 2014 Copyright © Seth Mensah Armah, 2014. All rights reserved. ii TABLE OF CONTENTS Page LIST OF ABBREVIATIONS ......................................................................................... iv ACKNOWLEDGEMENTS ...........................................................................................
    [Show full text]
  • Calcium Metabolism and Its Regulation
    OMICS Journals are welcoming Submissions OMICS International welcomes submissions that are original and technically so as to serve both the developing world and developed countries in the best possible way. OMICS Journals are poised in excellence by publishing high quality research. OMICS International follows an Editorial Manager® System peer review process and boasts of a strong and active editorial board. Editors and reviewers are experts in their field and provide anonymous, unbiased and detailed reviews of all submissions. The journal gives the options of multiple language translations for all the articles and all archived articles are available in HTML, XML, PDF and audio formats. Also, all the published articles are archived in repositories and indexing services like DOAJ, CAS, Google Scholar, Scientific Commons, Index Copernicus, EBSCO, HINARI and GALE. For more details please visit our website: http://omicsonline.org/Submitmanuscript.php Dr M Adak Professor of Biochemistry Anna Medical College and Research Center Mauritius Distribution Different Forms of Calcium Most of the calcium in the body exists as the mineral hydroxyapatite, Ca10(PO4)6(OH)2. Calcium in the plasma: 45% in ionized form (the physiologically active form) 45% bound to proteins (predominantly albumin) 10% complexed with anions (citrate, sulfate, phosphate) Both total calcium and ionized calcium measurements are available in many laboratories Body requirements Age (in years) Calcium Requirement 1 – 3 500mg 4 - 8 800mg 9 - 18 1300mg 19 - 50 1000mg 51+ 1500mg *Pregnant and lactating women are recommended a daily calcium intake of 1000mg. source Calcium is found in milk and dairy products, Green leafy vegetables, seafood, almonds, blackstrap molasses, broccoli, enriched soy and rice milk products, figs, soybeans and tofu.
    [Show full text]
  • Association of Vitamin D and FGF23 with Serum Ferritin in Hypoparathyroid Thalassemia: a Case Control Study
    Association of vitamin D and FGF23 with serum Ferritin in hypoparathyroid thalassemia: A case control study Forough Saki Shiraz University of Medical Sciences Azita Salehifar Shiraz University of Medical Sciences Seyed Reza Kassaee Shiraz University of Medical Sciences gholamhossein Ranjbar omrani ( [email protected] ) Shiraz University of Medical Sciences https://orcid.org/0000-0003-2224-7250 Research article Keywords: PTH, FGF23, ferritin, l,25(OH)2D3, hypoparathyroidism, major-beta thalassemia Posted Date: December 2nd, 2019 DOI: https://doi.org/10.21203/rs.2.17831/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Version of Record: A version of this preprint was published at BMC Nephrology on November 16th, 2020. See the published version at https://doi.org/10.1186/s12882-020-02101-3. Page 1/15 Abstract Background FGF23 controls serum l,25(OH) 2 D 3 levels and phosphate homeostasis. This study evaluates the effects of Ferritin on intact PTH, FGF23 and l,25(OH) 2 D 3 in patients with major thalassemia. It also evaluates FGF23 changes in patients with hypoparathyroidism to clarify the interaction between FGF23 and PTH in the absence of proper PTH function in human. Methods In this case-control study, 25 patients with major-beta thalassemia with hypoparathyroidism and their age- and gender-matched patients with major-beta thalassemia having normal parathyroid function were enrolled. Biochemical studies assessed the serum calcium, albumin phosphorus, alkaline phosphatase, PTH, FGF23, 25(OH)D, 1,25(OH)2D3, Ferritin and Fractional excretion of phosphorous. Results FGF23 was higher in the patients with hypoparathyroidism compared to the controls (p=0.002).
    [Show full text]